1. Field of the Invention
The present invention relates to drilling means utilizing fast moving tightly focused streams of a fluid such as water.
2. Description of the Prior Art
To the layman, "drilling" conjurs up a picture of a metal cylinder having cutting edges. Speed boat races have familiarized interested members of the public with the concept that at the speeds boats currently race, approximately 100-200 miles per hour, water can be considered for many purposes to have many of the characteristics of a solid. This was characterized by one racer in the following manner: "If you hit the water in the wrong way at high speeds, it's about as soft as hitting a brick wall."
Water has long been used for moving solids in selected manners. Among the well known uses over the past years have been sprays used to clean dishes, sprays used by dentists to clean mouths, and the home use water-pik.
Beginning primarily in the 1970s, a substantial amount of research has been done in boosting the pressure used to force water through relatively small orifices. Pressures as high as 50,000 psi have been obtained under laboratory conditions, which pressures have forced water through relatively tiny orifices at speeds in excess of the speed of sound in air at sea level to penetrate and fragment rock, concrete and similar materials. A partial list of hydrojet references includes:
1. N. Brooks, PhD., Sc. (eng), E. ENG., E. H. Page, PhD.m,B.Sc. (mining), "Energy Requirements for Rock Cutting by High Speed Water Jets," Dept. Mining and Mineral Sciences, Leads Univ., U.K. 1972 (energy, rock removal rates, jet traverse rates, high pressure jets).
2. J. H. Olson, PhD., "Jet Slotting of Concrete," Flow Research, Inc., USA, 1974, (Approx. weights of high pressure equipment, kerf-cutting depth, advance rate, stagnation pressure.)
3. Labus, T. J., Silks, W. M., "A Hydraulic Coal Mining Machine for Room and Pillar Applications", IIT Research Institute, USA (T. J. Labus); Goodman Equipment Corp., USA (W. M. Silks) 1976. (Total assembly and equipment selections).
4. Summers, D. A., B.Sc., PhD. C Eng., MIMM, D. J. Bushnell, PhD., "Preliminary Experimentation for the Design for the Water Jet Drilling Device", Univ. of Missouri-Rolla, USA, 1976 (Cutting attitude to bedding plane, nozzle angles, rotational r.p.m. feed rate, pressure, depth of penetration.)
5. Labus, T. J. "Energy Requirements for Rock Penetration by Water Jets," IIT Research Inst., USA, 1976 (Traverse rate, wall interaction, rock characteristics, specific impulse pressure).
6. Hilaris, J. A., Labus, T. J., "Highway Maintenance Application of Jet Cutting Technology," ITT Research Inst., USA (Hilaris, J. A.) and SCTRE Corp., USA (Labus, T. J.) 1978. (Nozzle geometry, multiple pass cutting, comparison with mechanical cutting).
7. Summers, D. A. and Lehnoff, T. F. and Weakly, L. A., "The Development of a Water Jet Drilling System and Preliminary Evaluations of its Performance in a Stress Situation Underground", Univ. of Missouri-Rolla, USA (Summers D. A. and Lehnoff, T. F.) St. Joe Mineral Corp. USA (Weakly, L. A.) 1978. (High pressure rock drilling, oil well drilling over 5,000 m., geothermal drilling, penetration rates, rock stresses).
8. Wolstad, O. M. Noecher, R. W., "Development of High Pressure Pumps and Associated Equipment for Fluid Jet Cutting", McCartney Manufacturing Co., Inc.
9. Cummins & Givens, SME Mining Engineering Handbook, Vol, I., 1973 (Section 11.0, drilling data and standard practices).
10. J. C. Bressee, Sc.D., J. D., G. A. Cristy, M. S., W. C. McClain PhD, "Some Comparisons of Continuous and Pulsed Jets for Excavation," Oak Ridge National Lab., USA, 1972. (Specific energy of continuous jet for different rocks and slurry concentrations).
11. B. Grossland, M.Sc., PhD., D.Sc., F. I. Mech.Eng., F. I. Prod. Eng., J. G. Logan, B.Sc.,PhD.m, "Development ot Equipment for Jet Cutting," Dept. of Mech. Eng., The Queen's Univ. of Belfast (Dr. Crossland), Coleraine Instrument Co., N. Ireland 9dr.Logan), 1972. (high pressure conical joints).
12. H. D. Harris, PhD., W. H. Brierly, "Application of Water Jet Cutting", National Research Council of Canada, DV. of Mech. Eng., Canada. (comparative costs of 3 arrays for kerf-cutting, nozzle size, materials).
13. S. C. Crow, P. V. Lade and G. H. Hurlburt, "The Mechanics of Hydraulic Rock Cutting", Univ. of Calif., USA, 1974. (stand-off dist., pressure, rock permeability and porosity).
14. H. Hamada, T. Fukuda, A. Sijoh, "Basic Study of Concrete Cutting by High Pressure Continuous Water Jets", Kobe Steel Co., Ltd., Japan, 1974. (specific energy, nozzle size, pressure, comprehensive strength).
A substantial number of patents have issued for various hydrojet applications, including:
U.S. Pat. No. 3,138,213 PA1 U.S. Pat. No. 3,141,512 PA1 U.S. Pat. No. 3,285,349 PA1 U.S. Pat. No. 3,396,806 PA1 U.S. Pat. No. 3,677,354 PA1 U.S. Pat. No. 3,424,256 PA1 U.S. Pat. No. 3,554,301 PA1 U.S. Pat. No. 3,650,338 PA1 U.S. Pat. No. 3,834,787 PA1 U.S. Pat. No. 3,567,222 PA1 U.S. Pat. No. 3,853,186 PA1 U.S. Pat. No. 3,857,449 PA1 U.S. Pat. No. 3,888,319 PA1 U.S. Pat. No. 3,908,045 PA1 U.S. Pat. No. 4,241,796
In spite of all this laboratory and applied research, and in spite of all of the patents which have already been issued, and in spite of what appeared to be tremendous theoretical advantages over prior art drills, hydrojet cutters have not yet had substantial impact. It would probably not be unfair to state that the prior art does not disclose any practical hydrojet rock cutter.
The reason for this apparent contradiction lies in the practical differences between operating a hydrojet cutter by skilled scientists and specialists under laboratory conditions and operating a similar hydrojet cutter in the field by oil drillers or persons of like skill and experience. Reliability which is sufficient in the laboratory is not sufficient in the field. Complications which are not too great in the laboratory are too great in the field. While it is possible to design, build, and operate under laboratory conditions a hydrojet cutter using pressures in excess of 50,000 psi, it is an entirely different matter in the field under field conditions. Hydrojet cutters will probably not be practical for many uses in the field until either technology improves so that the present highest technology laboratory run hydrojet cutters can have designed and built into them those characteristics necessary for operation in the field, or, the opposite situation, until some method can be found to permit hydrojet cutters which can be designed for use in the field to have the efficiency now found only in the more complex not yet practical for use in the field hydrojet cutters.
The present invention attempts to solve this not previously solved problem by giving a hydrojet cutter operating at 10,000 psi very nearly the cutting characterics of substantially more powerful hydrojet cutters by controlling the movement of a 10,000 psi hydrojet cutter in patterns such that shearing of material permits a 10,000 psi hydrojet cutter to do commercially substantially the same amount of work which with prior art designs, depending on the strata, might require as much as 50,000 psi. The use of the shear technique gives much the same advantage which is obtained by a skilled log chopper who knows the proper angle to chip pieces off the log in order to chop through a tree or log in a shorter time with less energy. The use of only a 10,000 psi hydrojet, of course, reduces the size of certain associated equipment and substantially reduces maintenance and wear problems thereby making what was previously not commercially reliable now commercially acceptable and reliable. The present system works because it attacks the rock or other material at its tensile strength, which is the weakest strength of most strata, rather than its compressive strength which is the strongest strength of most strata.